The high security achieved by using challenge and response methods and subscriber identity modules (SIM) for authentication of a high-security client in a mobile radio network goes along with high costs for development, production, personalization, administration and logistics of SIM Cards. For market segments in which the transmitted data volume amounts to only less than, e.g., ten kilobytes per client per year so that the volume of sales is very low compared to the costs for high security authentication, it is useful to pass on high security and accept a lower security for low-volume clients that only use a small data volume or have otherwise restricted or limited access. This is the case regarding low-volume clients used for machine-to-machine connections, e.g., an electric meter.
European Patent EP 1112666 B1 describes a method for improving the security of authentication procedures in digital mobile radio networks. The mobile radio network determines, by means of special algorithms and a SIM-specific secret code Ki, from a random number (as a challenge) an authentication result and a temporary code KC. If the high-security client wishes to log in, the mobile radio network transmits the random number to the subscriber identity module (SIM). The SIM determines, by means of the same, special algorithm and its SIM-specific secret code Ki, an associated authentication result and transmits the authentication result back to the mobile radio network (as a response). The mobile radio network compares the received authentication result to the stored authentication result for agreement, and in the case of agreement the high-security client is considered authenticated. The code KC calculated on both ends is used on both ends for decoding the transmission.
A drawback of the method mentioned above is that it goes along with high costs for development, production, personalization, administration and logistics of SIM Cards compared to the transmitted data volume that amounts to only some kilobytes per client per year.